Goldman Sachs CEO Lloyd Blankfein has been bullish on China for years, but at a briefing hosted by The Wall Street Journal on Wednesday morning he slammed the country’s handling of market forces as amateurish.

Blankfein said it was a “ham-handed way they dealt with the collapse,” referring to government intervention when the country’s stock market collapsed twice this summer.

“They don’t have a lot of experience at this market stuff.”

These are the harshest words about the Chinese economy we’ve heard from the generally optimistic Blankfein, and they get to the heart of how investors’ views on China have changed over the past few months.

Investors are starting to question how the Chinese government is managing its unique system.

But back to Blankfein. In an interview with Bloomberg TV back in July, he sounded more like his usual bullish self and asked host Stephanie Ruhle:

“Just as a thought experiment, thinking in the short-term and long-term, if I said you have to — Would you invest in China for the next year? — think of your answer to that question. And then if I said to you, you had to invest within, for 20 years, but you couldn’t touch it for 20 years — it was for your children — would you invest in China for the next 20 years?”

His point was that China was a great investment opportunity. That’s the standard line.

Back in 2013, when Goldman sold its stake in Chinese bank ICBC, he went on a media tour reiterating the bank’s bullish stance on the country’s future.

A year later, he told Charlie Rose that China’s rise already meant a new world order.

“Well, you know, you can look at it in the worst terms,” he said. “U.S. has a competitor. In the best terms, there’s no locus.”

But on Wednesday he sounded less optimistic, painting a picture of a clumsily managed economy.

China is focused on “10 per cent growth at any cost,” he said.

It’s a target out of reach for the foreseeable future. Most Wall Street analysts have Chinese gross-domestic-product growth sitting at around 6.5 per cent. Others say it’s actually somewhere around 4 per cent to 5 per cent.

Blankfein continued: “They’ll put a smoke belching factory in the middle of a city … In China, when they want to pump up their economy … they build 82 airports.”

He added that 30 of them would be in the wrong location.

Blankfein has always recognized that this way of allocating resources for growth is fundamental to the Chinese model. The question now is whether it’s a model the government can manage effectively.

At the briefing on Wednesday, one attendee asked Blankfein about China’s role as the biggest holder of U.S. debt. He responded that he would rather the Chinese have a stake in America’s future than vice versa.

“I’d rather they hold our debt than we hold their debt,” he said. “I’d rather owe money to the Chinese; they have a stake in our success. During the financial crisis they were worried about us. We weren’t worried about them.”